It is possible to finish this level without hitting any switches or killing any monsters at all. Run to the top of the level and jump the gorge. Off in the distance the save terminal can be seen but there's still lava on the ground. Jump anyway! But, when you land run into the adjoining room and hang a left. Keep running and get to the far right corner of the room. There's a switch there which will activate a platform and raise you out of the lava. At the top level of the platform there's another switch which will lover the lava around you. Once this happens just finish the level as usual...